Apparatus for controlling the atmosphere of the sterile chamber in an aseptic packaging machine

ABSTRACT

An apparatus for controlling the atmosphere of the sterile chamber in an aseptic packaging machine of the kind in which packaging material in web form is first brought in contact with a chemically acting sterilising liquid and is subsequently led through the interior of a sterile chamber inside which the packaging material is freed from liquid residues, and in which the packaging material is formed into a flexible tube and subdivided into individual, filled packages, in which the interior of the sterile chamber forms part of a flow circuit in which the mixture of chamber air and sterilising agent vapour forming the chamber atmosphere are circulated with the aid of a conveying means, in which further throttle means are provided between the chamber and conveying means for generating aboveambient pressure in the sterile chamber, and in which the circuit has means for limiting the concentration of the chemical sterilising agent in the atmosphere filling the sterile chamber.

United States Patent Loliger et al.

[ APPARATUS FOR CONTROLLING THE ATMOSPHERE OF THE STERILE CHAMBER IN ANASEPTIC PACKAGING MACHINE Inventors: Willi Loliger; Rudolf Schmied, bothof Konolfingen, Switzerland [73] Assignee: Alpura Koreco A. G.,Konolfingen,

Switzerland [22] Filed: July 7, 1972 [2]] Appl. No.: 269,518

10/1972 Garzotto 118/67 X 1' Dec. 17, 1974 Primary Examiner-JosephScovronek 7 Assistant Examiner-Arnold Turk Attorney, Agent, orFirmKenyon & Kenyon Reilly Carr & Chapin [5 7] I ABSTRACT An apparatusfor controlling the atmosphere of the sterile chamber in an asepticpackaging machine of the kind in which packaging material in web form isfirst brought in contact with a chemically acting sterilising liquid andis subsequently led through the' interior of a sterile chamber insidewhich the packaging material is freed from liquid residues, and in whichthe packaging material is formed into a flexible tube and subdividedinto individual, filled packages, in which the interior of thesterile'chamber forms part of a flow circuit in which the mixture ofchamber air and sterilising agent vapour forming the chamber atmosphereare circulated with the aid of a conveying means, in -which furtherthrottle means' are provided between the chamber and conveying means forgenerating aboveambientpressure in the sterile chamber, and in which thecircuit has means for limiting the concentration of the chemicalsterilising agent in the atmosphere filling the sterile chamber.

13 Claims, 3 Drawing Figures APPARATUS FOR CONTROLLING THE ATMOSPHERE OFTHE STERILE CHAMBER IN AN ASEPTIC PACKAGING MACHINE The inventionrelates to an apparatus for controlling the atmosphere of the sterilechamber in an aseptic packaging machine, of the kind in which packagingmaterial in web form is first brought in contact with a chemicallyacting sterilising liquid and subsequently led through the interior of asterile chamber inside which the packaging material is freed from liquidresidues, and in which the packaging material is formed into a flexibletube and subdivided into individual, filled packages.

There is a danger in an apparatus of the above type that thesterilisation liquid which is removed from the packaging material in theinterior of the sterile chamber may lead to an excessive concentrationof the sterilising agent in the chamber atmosphere. As a rule, hydrogenperoxide (H is employed as the sterilising agent. Thus, at an excessiveconcentration there is a danger that condensate formation from asupersaturated atmosphere may allow the chemical sterilising agent toenter the bottom of the packaging tube and hence the individual packs.Further, an excessive con-. centration can easily lead to explosions.Finally, the danger of corrosion is also very substantially increased ifthe chamber atmosphere is loaded excessively with the sterilising agent;

It is the aim of the invention to eliminate the described disadvantages.The apparatus according to theinvention is characterised in that theinterior of the sterile chamber forms part of a flow circuit in'whichthe mixture of chamber air and sterilising agent vapor forming thechamber atmosphere can be circulated with the aid ofa conveying means,in that further throttle means are provided between the chamber andconveying means for generating above-ambient pressure in the sterilechamber and in that the circuit has means for limiting the concentrationof the chemical sterilising agent in the atmosphere filling the sterilechamber.

A limitation of the concentrationof the chemical sterilising agent inthe sterile chamber atmosphere in the sense of the invention makes itpossible, by limiting the concentration to less than the dew pointconcentration, to prevent the formation of condensates that mayotherwise enter the packages together with the contents to be packagedand have a harmful effect on the contents. Furthermore, explosions canbe reliably eliminated and the danger of corrosion avoided.

-Suitably, the apparatus may be provided in such a way that a connectionwith the surrounding air exists between the throttle location and theconveying means by means of which environmental air can be introducedinto the circuit as a replacement for the mixture taken from theabove-ambient pressure portion of the circuit. By adjusting the ratio ofreplaced air and amount circulated, it is possible to limit theconcentration of the chemical sterilising agent in the atmospherefilling the sterile chamber in simple manner.

Further, the take-off point can be suitably located in the lowermostregion of the chamber and at the same time serve for dischargingcondensed sterilising agent. In a preferred embodiment, with a packagingmachine in which the packaging material is'formed into a flexible tube.inside the sterile chamber, an annular gap serving as throttle means atthe exit of the flexible tube from the sterile chamber between theflexible tube and parts of the sterile chamber bottom. A secondchambersurrounding the tube follows this annular gap, from which the circuitline leading to the conveying means branches off. The bottom of thesecond chamber forms a further annular gap together with the wall of theflexible tube through which the replacement air taken from thesurroundings can enter the circuit. A'n embodiment of this type preventsthe entry of organism-laden surrounding air into the interior of thesterile chamber in particularly efficient manner.

In the above described embodiment it is advisable also to subdivide thesecond chamber by means of a partition spaced away from the tube walland coaxial with the tube axis, a heater being located in the spacebetween the partition and the tube wall for volatilising liquidsterilising agent on the tube wall during the preliminary sterilisationof the apparatus.

The invention and its further features and advantages will now bedescribed in greater detail by means of the embodiments shown by way ofexample in the accompanying drawings, in which:

FIG. 1 is a vertical section of a packaging machine in which acontinuously fed paper web covered with plastics material is formed intoa tube in the interior of a sterile chamber and the tube is subdividedinto individual filled packages;

FIG. 2 shows an arrangement corresponding to that of FIG. 1 with analternative introduction of the replacement air; and

FIG. 3 shows a special construction of the annular gap between the tubewall and-the chamber bottom.

In the embodiment according to FIG. 1 a paper web 12 coated on one sidewith plastics material is continuously withdrawn from a supply roll 11,drawn through agents 17 are located which enable a slight aboveambientpressure to be maintained in the chamber 14. The web is led through ablowing device 15' in which heated sterile air from a line 18 is blownon both sides of the web at high speed through slotted pipes 16. Thesterilising liquid still adhering to the web 15 is in this way atomisedor volatilised into the chamber atmosphere.

After passing a direction changing roll 19, the web is, with the aid ofthe forming agents 20, 21 and 22, formed into a flexible tube which iswelded together along the sides of the web to form a closed tube. Airfor welding is aspired from the surroundings with the aid of a blower24, is heated with the aid of a heating spiral 25 and after passing asteriliser 26 is blown into a gap between the two overlappinglongitudinal edges with the aid of a hood 2 7. During this operation theplastics material located on the inside of the tube 23 is heated andcontact rolls 28 effect hermetic welding with formation of alongitudinal seam. A filling tube 29 protrudes into the interior-of thepackaging tube and-with its aid the tube 23 is filled approximately to alevel 30 with the sterile liquid to be packaged, e.g., pasteurized milk.With the aid of the revolving welding punches 31 the partly filled tubeis subdivided into individual filled packages. By using a correspondingwelder operating at right angles to the plane of the drawing tetrahedralpackages 32 are formed in known manner.

Before starting up the packaging machine the interior of the sterilechamber is subjected to a preliminary sterilisation, for example byspraying a chemically active sterilising liquid combined with thefeeding in of heated'air through the line 18.

The interior of the chamber 14 forms the component of a circuit in whichthe mixture of chamber air and sterilising agent vapor forming thechamber atmosphere is circulated with the aid of a conveying means suchas a fan 33. For this purpose the bottom 34 of the chamber 14 isdish-shaped and at the lowest point a discharge take-off line 35branches off and leads to a liquid separator 36. Separated liquid can bedischarged periodically by means of a tap 37. The mixture freed fromliquid droplets enters the fan 33 through a line 38 and subsequentlypasses through a line- 39 into a filter 40, in whose inlet chamber 41 anelectrically heated spiral heater 42 is located. From the filter 40, theconveyed medium returns to the chamber 14 via the line 18, namely intothe blowing device 16.

A throttle means 43 is located in the line 38 to generate a smallabove-ambient pressure of, for example, S-mm water head in the chamber14 while the fan 33 is running. A means for limiting the concentrationof the chemical sterilizing agent in the atmosphere filling the sterilechamber includes a line 44 which connects into the line 38 between thethrottle means 43 and the fan 33 and through it fresh air from thesurroundings can enter the described circuit. A float-type fl'ow meterair from the surroundings enters the circuit through the line 44 toreplace the mixture discharged from the circuit. By suitably adjustingthe blow-off valve 47, the concentration of the chemical sterilisingagent in the atmosphere filling the chamber 14 can be controlled insimple manner. When a 10 to 40 percent solution of hydrogen peroxide isused, it is advisable to maintain a concentration of 25 g per L000 g ofair in the chamber 14. Such a value on the one hand reliably eliminatesthe disadvantages described at the outset and on the other hand ensuresmore certain aseptic operation where a leak allows an organism topenetrate into the interior.

During operation of the described apparatus the temperature of themixture fed in through the line 18 is suitably 120C. To reach thepreferredconcentration of sterilising agent in the chamber atmosphere, aratio of circulated mixture to introduced replacement air of about 2 2 Ihas been found to be suitable.

in the arrangement according to FIG. 2 wherein like reference charactersindicate like parts as above the throttling corresponding to thethrottle means of FIG. 1 is obtained with'a gap 51 between the flexibletube 23 and the open bottom 34 of the chamber 14. The meansfor limitingthe concentration of sterilizing agent in the atmosphere filling thechamber includes a second chamber 52 which surrounds the tube 23 andfollows on the annular gap 51 and from it the line 54 leading to theseparator 53 branches off. The bottom 55 of the second chamber forms afurther annular gap 56 together with the flexible tube wall, throughwhich the replacement air taken from the surroundings can enter thecircuit'The air entering by the gap 56 prevents any mixtures of air andsterilising agent from leaking outside.

in correspondence with FIG. 1 this circuit uses a conveying means in theform of a fan 57 and a filter means 58 with heating coil 59 from whichthe sterile mixture of air and sterilising agent vapor enters theblowing device 15, 16 via a line 60. An indicating meter 62 is locatedin a line 61 between the separator 53 and the conveying means 57.

From the lowest point of the bottom 34, a ,line'63 branches off and isclosed with the aid of a valve means such as a weighted flap 64. Aweight 65 is adjusted in such a way that at a predetermined pressure,chamber atmosphere is blown off. Non-condensed portions are condensedwith the aid of cold water fed into an injection condenser 67, through aline 68.

By a suitable dimensioning of the annular gap 51 in .the embodimentaccording to FIG. 2 a definite concentration of sterilising agent isonce more maintained in the atmosphere of the chamber 14. For thepreliminary sterilisation, the chamber 52 is subdivided into two annularspaces with the air of a wall 71 coaxial with the axis of the flexibletube, an electrical spiral heater 73' being located in the annular space72 between wall 71 and tube 23. This heater 73 serves to volatilize theliquid sterilising agent depositing on the walls of the flexible tubeduring the preliminary sterilizing of the chamber 14. in this waysterilising agent having a corrosive action is prevented from enteringthe sensitive device' for producing the transverse welding seams.

FIG. 3 shows details 'of a suitable construction-for forming the gapbetweenthe flexible tube 23 and the bottom of thesterile chamber. Here,cutting edges 82 are coaxial with the axis of the flexible tube 23 onthe bottom 81 of the sterile chamber (not shown). On the cutting edges82 rests a plate 83, whose bore 84 is dimensioned such that an annulargap 85 of predetermined width is formed between the tube and the bore84. The plate 83 resting on the cutting edges 82 can follow smalllateral movements of the tube 23.

The invention is not limited to the described embodi ments. in a furtherembodiment, the concentration of the chemical sterilising agent islimited in the chamber by a chemical'substance .or composition in thecircuit,

e.g., metal fillings, which is able to bind or catalytically decomposethe sterilising agent or an undesirable component of the same in such away that no undesired concentration can arise in the chamber.

We claim:

1. In combination with an aseptic packaging machine having a sterilechamber in which a packaging material is formed into a flexible tube; anapparatus for control-- ling the atmosphere of said sterile chambercomprising a flow circuit including said sterile chamber for a flow of amixture of chamber air and sterilizing agent vapor forming the chamberatmosphere, a conveying means in said flow circuit for recirculating theflow, throttle means between said chamber and said conveying means forgenerating an above-ambient pressure in said chamber, and means forlimiting the concentration of the sterilizing agent in the atmospherefilling said chamber.

2. The combination as set forth in claim 1 which further comprises adischarge line connected to said chamber at a lower end thereof fordischarging condensed sterilizing agent therefrom.

3. The combination as set forth in claim 1 which further comprises aliquid separator connected to said flow circuit between said chamber andsaid conveying means.

4. The combination as set forth in claim 1 which further comprises meansin said flow circuit for sterilizing the flow passing from saidconveying means into said sterile chamber.

5. The combination as set forth in claim 1 wherein said means forlimiting said concentration includes a line connected to said flowcircuit between said throttle means and said'conveying means forintroducing surrounding air into said flow circuit.

6. The combination as set forth in claim 5 wherein said means forlimiting said concentration further includes a line connected to saidflow circuit upstream of said throttle means and an adjustable blow-offvalve in said line for discharging the chamber atmosphere when apredetermined pressure is exceeded in said chamber.

7. The combination as set forth in claim '5 which further includes aflow meter in said line for indicating the amount of surrounding airintroduced into said flow circuit through said line.

8. The combination as set forth in claim 1 wherein said means forlimiting said concentration includes a second chamber in said flowcircuit downstream of said throttle means for passage of the flexibletube therethrough, said second chamber having an open bottom to define agap with the flexible tube for introducing surrounding air into saidflow circuit.

9. The combination as set forth in claim 8 wherein said throttle meansis a gap between an open bottom of a flow circuit including said sterilechamber for a flow of a mixture of chamber air and sterilizing agentvapor forming the chamber atmosphere,

a fan in said flow circuit for recirculating the flow,

throttle means between said chamber and said fan for generating anabove-ambient pressure in said chamber, I

an adjustable blow-off valve connected to said flow circuit upstream ofsaid throttle means to allow chamber atmosphere to discharge when apredetermined pressure is exceeded in said chamber, and r a lineconnected to said flow circuit between said throttle means and saidconveying means for introducing surrounding air into said. flow circuitto replace the atmosphere discharged through said blow-off valve.

- 12. In combination with an aseptic packaging machine having a sterilechamber in which a packaging material is formed into a flexible tube; anapparatus for controlling the atmosphere of said sterile chambercomprising a flow circuit including said sterile chamber for a flow of amixture of chamber air and sterilizing agent vapor forming the chamberatmosphere,

a conveying means in said flow circuit for recirculating the flow,

throttle means between said chamber and said con-- 13. The combinationas set forth in claim 12 which further comprises a partition in saidsecond chamber coaxially of the path of the flexible tube forsubdividing said second chamber, and a heater within said partition forvolatilizing liquid sterilizing agent on the outer surface of theflexible tube.

1. In combination with an aseptic packaging machine having a sterilechamber in which a packaging material is formed into a flexible tube; anapparatus for controlling the atmosphere of said sterile chambercomprising a flow circuit including said sterile chamber for a flow of amixture of chamber air and sterilizing agent vapor forming the chamberatmosphere, a conveying means in said flow circuit for recirculating theflow, throttle means between said chamber and said conveying means forgenerating an above-ambient pressure in said chamber, and means forlimiting the concentration of the sterilizing agent in the atmospherefilling said chamber.
 2. The combination as set forth in claim 1 whichfurther comprises a discharge line connected to said chamber at a lowerend thereof for discharging condensed sterilizing agent therefrom. 3.The combination as set forth in claim 1 which further comprises a liquidseparator connected to said flow circuit between said chamber and saidconveying means.
 4. The combination as set forth in claim 1 whichfurther comprises means in said flow circuit for sterilizing the flowpassing from said conveying means into said sterile chamber.
 5. Thecombination as set forth in claim 1 wherein said means for limiting saidconcentration includes a line connected to said flow circuit betweensaid throttle means and said conveying means for introducing surroundingair into said flow circuit.
 6. The combination as set forth in claim 5wherein said means for limiting said concentration further includes aline connected to said flow circuit upstream of said throttle means andan adjustable blow-off valve in said line for discharging the chamberatmosphere when a predetermined pressure is exceeded in said chamber. 7.The combination as set forth in claim 5 which further includes a flowmeter in said line for indicating the amount of surrounding airintroduced into said flow circuit through said line.
 8. The combinationas set forth in claim 1 wherein said means for limiting saidconcentration includes a second chamber in said flow circuit downstreamof said throttle means for passage of the flexible tube therethrough,said second chamber having an open bottom to define a gap with theflexible tube for introducing surrounding air into said flow circuit. 9.The combination as set forth in claim 8 wherein said throttle means is agap between an open bottom of said sterile chamber and the flexibletube.
 10. The combination as set forth in claim 8 which further includesa flow meter in said flow circuit between said throttle means and saidconveying means.
 11. In combination with an aseptic packaging machinehaving a sterile chamber in which a packaging material is formed into aflexible tube; and apparatus for controlling the atmosphere of saidsterile chamber comprising a flow circuit including said sterile chamberfor a flow of a mixture of chamber air and sterilizing agent vaporforming the chamber atmosphere, a fan in said flow circuit forrecirculating the flow, throttle means between said chamber and said fanfor generating an above-ambient pressure in said chamber, an adjustableblow-off valve connected to said flow circuit upstream of said throttlemeans to allow chamber atmosphere to discharge when a predeterminedpressure is exceeded in said chamber, and a line connected to said flowcircuit between said throttle means and said conveying means forintroducing surrounding air into said flow circuit to replace theatmosphere discharged through said blow-off valve.
 12. In combinationwith an aseptic packaging machine having a sterile chamber in which apackaging material is formed into a flexible tube; an apparatus forcontrolling the atmosphere of said sterile chamber comprising a flowcircuit including said sterile chamber for a flow of a mixture ofchamber air and sterilizing agent vapor forming the chamber atmosphere,a conveying means in said flow circuit for recirculating the flow,throttle means between said chamber and said conveying means forgenerating an above-ambient pressure in said chamber; a valve meansconnected to said sterile chamber for blowing off chamber atmosphere ata predetermined pressure thereof, and a second chamber in said flowcircuit downstream of said throttle means for passage of the flexibletube therethrough, said second chamber having an open bottom to define agap with the flexible tube for introducing surrounding air into saidflow circuit to replace the atmosphere discharged through said valvemeans.
 13. The combination as set forth in claim 12 which furthercomprises a partition in said second chamber coaxially of the path ofthe flexible tube for sub-dividing said second chamber, and a heaterwithin said partition for volatilizing liquid sterilizing agent on theouter surface of the flexible tube.